Microsomal glycerolphosphate acyltransferase inactivation by fatty acids.
Glycerolphosphate acyltransferase activity in microsomes from rat adipose tissue is shown to decrease with time upon incubation with adipose tissue cytosolic fraction. The inactivation can be prevented with serum albumin and seems to be caused by an increase in endogenous free fatty acid as a consequence of the action of cytosolic lipase(s) on the membrane lipids. Similar inactivation can be observed after short incubation of microsomes with oleic acid at micromolar concentrations. Diacylglycerol acyltransferase is also inhibited by oleic acid, although to a lesser degree. In contrast, glucose-6-phosphatase and NADPH-cytochrome reductase activities are not changed. The oleic acid effect appears to occur upon binding to the microsomal membranes and can be prevented by bovine serum albumin at protein/fatty acid molar ratios above one. These results suggest that free fatty acids may be involved in the modulation of triacylglycerol synthetic enzymes.
Durocher
V
V
McGill Unit for the Prevention of Cardiovascular Disease, McGill University, Montreal, Que., Canada.
Miller
M
M
Rodriguez
M A
MA
D000217:Acyltransferases / Q000378:metabolism; D000273:Adipose Tissue / Q000201:enzymology; D000818:Animals; D003600:Cytosol / Q000201:enzymology; D051048:Diacylglycerol O-Acyltransferase; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism*; D008049:Lipase / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000201:enzymology* / Q000378:metabolism; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D010168:Palmitates / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
D005230:Fatty Acids, Nonesterified; D009829:Oleic Acids; D010168:Palmitates; C050015:4-nitrophenyl palmitate; D012710:Serum Albumin, Bovine; D019301:Oleic Acid; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase; D051048:Diacylglycerol O-Acyltransferase; D008049:Lipase